"The BMW M5 is keener to knuckle down and be serious. Its 592bhp lags slightly behind the E63S, but it feels more agile, and to a greater degree than its slim 25kg weight advantage suggests. It favours assertiveness over aggression, and its steering is quicker, its pedals more responsive and its front tyres more willing to bite. That also means it can snap a bit quicker than the Merc, which seems to slide in slow-motion. The M5’s engine has sound fed into the cabin, and it’s sharper and higher pitched. The thunderous AMG appears to be gargling its own mechanical components in comparison....
The BMW remains a touch more serious, and the more cossetting car, while the Merc’s a touch more aloof, more willing to have fun. The M5 may be the one piping its sound through the speakers, but it’s the E63S that bombards you with engine noise, even at sedate speeds. It’s the one I can’t help immaturely hoofing out of junctions, V8 rumble soundtracking a quarter-turn of opposite lock. While the pair’s performance and abilities are impossible to split, the attitude they encourage from their driver is starting to diverge....
Even after 1,500 miles, I’m torn. The BMW is the more rounded, comfy car. It covers all bases with a staggering depth of engineering, and might well be the most complete sports saloon ever. To an enthusiast, though, such completeness can be a help and a hindrance. The Merc is less couth, bigger hearted and encourages its driver to be more playful. Particularly if they’re on a frozen lake. Oh, and it comes as an estate, too. The AMG edges it.'
https://www.topgear.com/car-news/big...aloon-slugfest